1. Field Of The Invention
This invention relates to lead-acid cells and to sealed lead-acid cells, and, more particularly, to a modular cabinet for housing such cells.
2. Description Of The Prior Art
Stationary batteries are specifically designed for float applications, that is, as standby power in the event of a power failure. Stationary batteries are usually maintained at a full-state-of-charge and in a ready-to-use condition typically by floating at a constant preset voltage. Standby batteries are used for standby or operational power in the communications field, utilities, for emergency lighting in commercial buildings and uninterruptible power supplies.
Uninterruptible power supplies are systems that back-up computers and communication networks. Sealed lead-acid cells and/or batteries may comprise the power source. The uninterruptible power source allows for the orderly shut down of computers when there is a sudden interruption in the primary electrical source, such as during a power outage and provides back-up power for communications networks. The uninterruptible power supply also will accommodate short, or intermittent, losses in power. When there is a power interruption, the batteries in the uninterruptible power system can be subject to rapid discharge.
The sealed lead-acid stationary cells and/or batteries used for industrial applications where the power requirements are high and quite demanding are typically comprised of from several to a large number of individual sealed lead-acid cells connected to one another to form a battery with the desired capacity and power requirements. The individual sealed lead-acid cells may be connected in series, in parallel or in suitable combinations of series and parallel to form a battery with the desired capacity and power requirements. External connections are typically made between the negative and positive terminal posts of the respective cells.
For many applications, the lead-acid cells used must be capable of delivering the necessary electrical power at a high rate. Thus, for example, high rate applications may involve discharging the lead-acid cells to an eighty percent depth of discharge in a period of time of from about 1 to 15 minutes or so.
Such applications may require utilizing, for example, anywhere from about 180 to 240 cells or so. At perhaps the other end of the application range, many situations require from about 24 to 48 cells or so.
The weight of lead-acid cells used for such high rate applications can vary considerably. However, each individual cell may, for example, weigh from about 30 to 60 pounds or more.
Because of space considerations, these large capacity cells need to be placed on racks, cabinets or the like in an attempt to minimize the space requirements. Height limitations in some locations also present a problem for providing racks for the number of cells required, given the available floor space. A complicating factor is that, due to the weight of the cells, the cell rack or cabinet must be extremely sturdy in construction and stable in use. Still further, for Zone 4 applications, i.e., locations where high seismic conditions can occur, there are even further stringent requirements that must be met to insure that the cells are adequately secured in the racks should such high seismic conditions occur.
Flexibility is also required because the specific applications require many different configurations. Also, when configured in a particular application, all of the cells must be easily accessible for testing, replacement when necessary, and for other maintenance and/or checking purposes.
A particularly useful cell for uninterruptible power supply applications is disclosed in the pending Shaffer et al. application, Ser. No. 07/803,349, filed Dec. 4, 1991, for: "Novel Sealed Lead-Acid Cell Having A Novel Lug, And End Cover Assembly" now U.S. Pat. No. 4,227,266. The unique cells disclosed have numerous significant advantages, including providing a battery having increased capacity and more efficient utilization of the internal space within the cell.
The lead-acid cell racks available, however, do not even adequately meet the objectives for current lead-acid cells, much less the unique cells described in the copending Shaffer et al. application.
It is accordingly a principal object of the present invention to provide a modular cell rack assembly capable of housing cells used for standby applications such as uninterruptible power supply applications.
A further object is to provide a modular cell rack assembly which minimizes the floor space requirements for the number of cells involved for a particular application.
Another object of the present invention lies in the provision of a modular cell rack assembly which is inexpensive, may be readily manufactured, and is easy to utilize in the field.
Yet another object of the present invention provides a modular cell rack assembly in which each cell retained in the assembly is readily accessible.
A still further object is to provide a modular cell rack assembly that is safe in use, essentially eliminating the possibility that terminal-to-terminal contact with metal could occur, resulting in a shock or the like to personnel handling the cells.
Yet another object lies in the provision of a modular cell rack assembly in which the cells are securely held so as to satisfy requirements for high seismic locations.
These and other objects and advantages of the present invention will be apparent from the following description and drawings.